Preliminary results are presented for a performance trial in eastern Colorado for a 6-GHz, 128-QAM, 155-Mb/s digital radio system. This system, which uses the standard North American 30-MHz channelization plan for 6 GHz, used 128-QAM modulation to maximize system gain, minimize the impact of foreign system interference, and provide the capability to transport the 155-Mb/s, OC-3 SONET payload structure with a very low residual background bit-error-rate. The results provide a preliminary view of 128-QAM digital radio performance in a fading environment, including errored second (ES) and severe errored second (SES) performance.<<ETX>>